Justin Bieber vs. Seth Rogen and Other Memorable Celebrity Feuds

In fact, during a recent interview with Howard Stern, the funnyman said Biebs is "a little bit of a motherf--ker. Whatever. He's a bit of a d--k." Of course, this isn't exactly shocking considering Rogen called the young pop star a "piece of s--t" earlier in the year.

But J.B. finally responded to all the shade thrown his way, tweeting on Thursday, "Seth Rogan (sic) sorry I didnt bow down when I asked 2 meet u was probably a bit shy and didn't want to be over the top but still. love ur movies." (Hm, didn't expect that last part.)

After witnessing their exchange, we couldn't help but reminisce on some more memorable celeb feuds. Take a look!

Kate Upton vs. Carol Alt: The model seemed to take a slight dig at 21-year-old when she told HuffPost Live, "What I don't understand with Kate is, what's all the hullabaloo?" Regarding Upton, the 53-year-old brunette beauty said, "I think what it is, is that in this moment there's just so much social media and that's why she's had more word of mouth than anybody." But she was quick to add, "I like Kate. She's a pretty girl." Nice save.

Mark Davis/Getty Images

Kanye West vs. Jimmy Kimmel: Sure, the late-night talk show host is known for his pranks (Hi, Sochi!), but this spat wasn't one of them. The rapper apparently saw no humor whatsoever in Kimmel's parody of his interview with BBC Radio One, in which he referred to himself as the "No. 1 rock star on the planet." Yeezy proceeded to voice his anger by way of Twitter, to which Kimmel replied, "Finally, I'm in a rap feud."

Paul Drinkwater/NBC, AP Images/Invision

Tina Fey and Amy Poehler vs. Taylor Swift: At the 2013 Golden Globes, the show's cohosts couldn't help but poke fun at the singer's love life by telling her to stay away from Michael J. Fox's son. The joke didn't exactly go over too well with the country crooner who later remarked, "You know, Katie Couric is one of my favorite people. Because she said to me she had heard a quote that she loved that said, 'There's a special place in hell for women who don't help other women.'"

Michael Becker / FOX

Mariah Carey vs. Nicki Minaj: These two ladies certainly gave new meaning to the term 'catfight' when they both served as judges on American Idol. "Honestly, I hated it," Carey said during a radio interview of her single season on the Fox show. "I thought it was going to be a three-person panel. They gave me a nice dangling monetary moment, and I was just like, 'Okay. Randy Jackson will be there; I've known him forever. He used to play bass for me. Like, this isn't a big deal. This will be nothing.' But it wasn't that. It was like going to work every day in hell with Satan."

Getty Images/Frazer Harrison/WireImage

Sinéad O'Connor vs. Miley Cyrus: Both artists went back and forth after the "Nothing Compares 2 U" crooner wrote an open letter to Cyrus and lashed out at her oversexualized image. Cyrus, in turn, took to Twitter to slam O'Connor, who then penned yet another letter (actually, make that a fourth letter!) to the "We Can't Stop" singer, in which she blasted Cyrus for "stigmatizing mental illness."

Keith Hewitt/FilmMagic, Christopher Polk/Getty Images

Lady Gaga vs. Adam Levine: The Maroon 5 frontman seemed to take a dig at Mother Monster when he tweeted, "Ugh..recycling old art for a younger generation doesn't make you an artist. It makes you an art teacher," followed by, "I unabashedly love writing and performing pop music for both myself AND everyone around me. That's it. It doesn't need any extra sauce." Believing the tweets were directed at her, Gaga snapped back, writing, "uh oh guys the art police is here."